In a magnetic disk device, a control device configured to control read/write of data from/to the magnetic disk is provided. This control device is connected to a regulator device and, electric power is output from the regulator device to the control device, whereby the control device operates. Accordingly, the control device needs to set an output voltage of the regulator device.
Here, a technique for setting a power supply voltage by transmitting a voltage value necessary for the control device to the regulator device through a serial interface such as an I2C or the like is known. However, the regulator device varies in the output voltage accuracy. Further, even if the power supply voltage is constant, the internal circuit of the control device varies in the operating frequency, and hence regarding the voltage output from the regulator device, the variation in the control device also needs to be taken into consideration. Accordingly, the control device has hitherto set the output voltage of the regulator device, i.e., the power supply voltage by taking the output variation of the regulator device into consideration in addition to the operable voltage of the power source regarding which the variation in the operating frequency of the internal circuit is taken into consideration.
Incidentally, when the power supply voltage is to be set as described previously, transmitting a voltage value from the control device to the regulator through a serial interface is conceivable. However, when the serial interface is used, the response speed of the regulator becomes low due to the influence of the communication speed. For this reason, it becomes impossible to carry out voltage correction in real time.
Further, when the power supply voltage is to be set as described previously, transmitting parallel signals formed by uniquely assigning a power supply voltage value to parallel signals from the control device to the regulator through a parallel interface is also conceivable. By doing so, it is possible to make the response speed of the regulator higher than the case of the serial interface. However, when the parallel interface is used, due to uniquely assigning the power supply voltage value to the parallel signals, the voltage variation steps depends on the number of passes. Accordingly, when it is aimed to vary the voltage by way of the parallel interface, the voltage variation steps become coarse, and thus it becomes possible to only roughly and coarsely carry out correction of the output voltage of the regulator.
The problem which the present invention aims to solve is to provide a magnetic disk device, regulator device, and control device capable of correcting the output voltage of the regulator device to the control device in real time with a high degree of accuracy.